Question: A jar contains $9$ red jelly beans, $3$ green jelly beans, and $9$ blue jelly beans. If a jelly bean is randomly chosen, what is the probability that it is not blue?
There are $9 + 3 + 9 = 21$ jelly beans in the jar. There are $9$ blue jelly beans. That means $21 - 9 = 12$ are not blue. The probability is $ \frac{12}{21} = \dfrac{4}{7}$.